CN111033287B - Fault diagnosis method, motor control method, power conversion device, motor module, and electric power steering device - Google Patents

Fault diagnosis method, motor control method, power conversion device, motor module, and electric power steering device Download PDF

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Publication number
CN111033287B
CN111033287B CN201880052833.9A CN201880052833A CN111033287B CN 111033287 B CN111033287 B CN 111033287B CN 201880052833 A CN201880052833 A CN 201880052833A CN 111033287 B CN111033287 B CN 111033287B
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switching element
failure diagnosis
phase
equal
failure
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CN111033287A (en
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A·哈德利
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Nidec Corp
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Nidec Corp
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    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M7/00—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
    • H02M7/42—Conversion of dc power input into ac power output without possibility of reversal
    • H02M7/44—Conversion of dc power input into ac power output without possibility of reversal by static converters
    • H02M7/48—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode

Abstract

The failure diagnosis method according to the embodiment diagnoses whether or not a switching element, which is repeatedly switched between on and off, of an electrical device has a failure. The fault diagnosis method comprises the following steps: determining whether or not a current flowing in the switching element when the switching element is controlled to the on state is smaller than a prescribed current; detecting a time when the current flowing through the switching element is smaller than a predetermined current when the current flowing through the switching element is smaller than the predetermined current; determining whether the detected time is equal to or longer than a predetermined time; counting the number of times that the detected time is equal to or longer than a predetermined time when the detected time is equal to or longer than the predetermined time; determining whether the counted total number of times is equal to or greater than a predetermined number of times; and determining that the switching element has failed when the counted total number of times is equal to or greater than the predetermined number of times.

Description

Fault diagnosis method, motor control method, power conversion device, motor module, and electric power steering device
Technical Field
The present disclosure relates to a failure diagnosis method, a motor control method, a power conversion device, a motor module, and an electric power steering device.
Background
In recent years, an electromechanical motor (hereinafter, simply referred to as "motor") in which an electric motor, an inverter, and an ECU are integrated has been developed. In the field of vehicle mounting in particular, it is required to ensure high quality from the viewpoint of safety. Therefore, a redundant design is introduced which can continue to operate safely even if a part of the component fails. As an example of the redundant design, a design in which 2 power conversion devices are provided for 1 motor has been studied. As another example, a design in which a backup microcontroller is provided for a main microcontroller has been studied.
Patent document 1 discloses a motor drive device having a1 st system and a2 nd system. The 1 st system is connected to the 1 st coil group of the motor, and includes a1 st inverter unit, a power supply relay, a reverse connection protection relay, and the like. The 2 nd system is connected to the 2 nd coil group of the motor, and includes a2 nd inverter unit, a power supply relay, a reverse connection protection relay, and the like. When the motor driving device is not failed, the motor can be driven using both the 1 st system and the 2 nd system. In contrast, when one of the 1 st system and the 2 nd system or one of the 1 st coil group and the 2 nd coil group fails, the power supply relay cuts off the supply of electric power from the power supply to the failed system or the system connected to the failed coil group. The motor can be continuously driven by the other system which has not failed.
Patent documents 2 and 3 also disclose a motor drive device having the 1 st system and the 2 nd system. Even if one system or one coil group has a failure, the motor can be continuously driven by the system in which no failure has occurred.
Patent document 4 discloses a motor drive device that has 4 electrical separation members and 2 inverters and converts electric power supplied to a three-phase motor. For 1 inverter, 1 electrically isolating member is provided between the power supply and the inverter, and 1 electrically isolating member is provided between the inverter and the ground (hereinafter, referred to as GND). The motor can be driven by the inverter that has not failed using the neutral point of the coil in the inverter that has failed. At this time, the 2 electrically isolating members connected to the failed inverter are set to the off state, and the failed inverter is isolated from the power supply and GND.
Documents of the prior art
Patent document
Patent document 1: japanese patent laid-open publication No. 2016-34204
Patent document 2: japanese patent laid-open publication No. 2016 & 32977
Patent document 3: japanese patent laid-open No. 2008-132919
Patent document 4: japanese patent No. 5797751
Disclosure of Invention
Problems to be solved by the invention
In a device that drives a motor using the power conversion device as described above, when the power conversion device fails, it is required to identify the failure site.
For example, when a switching element included in the power conversion device has failed, it is required to determine which switching element of the plurality of switching elements has failed. For example, when a power conversion device that supplies power to a motor having n-phase (n is an integer equal to or greater than 3) coils fails, it is required to determine which of the plurality of phases has failed.
Embodiments of the present disclosure provide a fault diagnosis method that can determine which switching element of a plurality of switching elements has failed when a fault has occurred.
Further, the embodiments of the present disclosure provide a fault diagnosis method capable of determining which phase among a plurality of phases has a fault when a fault has occurred.
Means for solving the problems
An exemplary failure diagnosis method of the present disclosure diagnoses whether or not a switching element, which is repeatedly switched on and off, of an electrical device has a failure, and includes: determining whether or not a current flowing in the switching element when the switching element is controlled to the on state is smaller than a prescribed current; detecting a time when the current flowing in the switching element is smaller than the predetermined current, when the current flowing in the switching element is smaller than the predetermined current; determining whether the detected time is equal to or longer than a predetermined time; counting the number of times that the detected time is equal to or longer than the predetermined time, when the detected time is equal to or longer than the predetermined time; determining whether or not the counted total number of times is equal to or greater than a predetermined number of times; and determining that the switching element has failed when the counted total number of times is equal to or greater than the predetermined number of times.
Effects of the invention
According to the embodiments of the present disclosure, when a failure occurs, it is possible to determine which switching element of the plurality of switching elements has failed.
Further, according to the embodiments of the present disclosure, when a failure occurs, which phase of the plurality of phases has failed can be determined.
Drawings
Fig. 1 is a block diagram schematically illustrating a representative block structure of a motor module 2000 of exemplary embodiment 1.
Fig. 2 is a circuit diagram schematically showing a circuit configuration of the inverter unit 100 of the exemplary embodiment 1.
Fig. 3 is a graph illustrating a current waveform (sine wave) obtained by plotting current values of currents flowing through the respective coils of the a-phase, B-phase, and C-phase of the motor 200 when the inverter unit 100 is controlled in accordance with the three-phase energization control.
Fig. 4 is a functional block diagram illustrating functional blocks of the controller 340 for performing overall motor control.
Fig. 5 is a flowchart showing an operation for diagnosing whether or not a failure occurs in the switching element using the value of the current flowing through the switching element.
Fig. 6 is a diagram for explaining an example of an operation for diagnosing whether or not the switching element has a failure by using a value of a current flowing through the switching element.
Fig. 7 is a diagram showing the relationship among the output value of the AND block 822, the output value of the integrator 831, AND the output value of the comparator 841.
Fig. 8 is a diagram showing the relationship among the output value of the AND block 822, the output value of the integrator 831, AND the output value of the comparator 851.
Fig. 9 is a flowchart showing an operation for diagnosing whether or not the switching element has a failure by using the value of the voltage applied to the switching element.
Fig. 10 is a diagram illustrating an example of an operation for diagnosing whether or not a failure occurs in the switching element using a value of a voltage applied to the switching element.
Fig. 11 is a diagram showing the controller 340 for diagnosing whether or not the switching element has a failure using both the current value and the voltage value.
Fig. 12 is a diagram showing an example of a functional block of the failure diagnosis unit 800_ IV.
Fig. 13 is a diagram showing another example of the functional blocks of the failure diagnosis unit 800_ IV.
Fig. 14 is a diagram showing the controller 340 for diagnosing whether a phase has a fault using a current value.
Fig. 15 is a diagram showing an example of functional blocks of the failure diagnosis unit 800P _ I.
Fig. 16 is a diagram showing an example of functional blocks of the failure diagnosis unit 800P _ IA.
Fig. 17 is a diagram showing the controller 340 that diagnoses the presence or absence of a phase failure using the voltage value.
Fig. 18 is a diagram showing an example of functional blocks of the failure diagnosis unit 800P _ V.
Fig. 19 is a diagram showing an example of functional blocks of the failure diagnosis unit 800P _ VA.
Fig. 20 is a diagram showing the controller 340 for diagnosing whether or not a phase has failed using both the current value and the voltage value.
Fig. 21 is a diagram showing an example of functional blocks of the failure diagnosis unit 800P _ IV.
Fig. 22 is a diagram showing another example of the functional blocks of the failure diagnosis unit 800P _ IV.
Fig. 23 is a circuit diagram schematically illustrating a circuit configuration of an inverter unit 100A having a single inverter 140 according to a modification of embodiment 1.
Fig. 24 is a schematic diagram showing a typical configuration of an electric power steering apparatus 3000 according to embodiment 2.
Detailed Description
Hereinafter, embodiments of a failure diagnosis method, a motor control method, a power conversion device, a motor module, and an electric power steering device according to the present disclosure will be described in detail with reference to the drawings. However, unnecessary detailed description is sometimes omitted in order to avoid unnecessary redundancy in the following description and to facilitate understanding by those skilled in the art. For example, detailed descriptions of well-known matters and repetitive descriptions of substantially the same structures may be omitted.
In the present specification, an embodiment of the present disclosure will be described by taking as an example a power conversion device that converts power from a power supply into power to be supplied to a three-phase motor having three-phase (a-phase, B-phase, and C-phase) coils. However, a power conversion device that converts power from a power source into power to be supplied to an n-phase motor having four-phase or five-phase equal n-phase (n is an integer of 4 or more) coils and a motor control method for the device are also within the scope of the present disclosure.
(embodiment mode 1)
[ 1 ] Structure of Motor Module 2000 and Power conversion device 1000 ]
Fig. 1 schematically shows a representative block structure of a motor module 2000 of the present embodiment.
The motor module 2000 representatively has a power conversion device 1000 and a motor 200. The power conversion apparatus 1000 has an inverter unit 100 and a control circuit 300. The motor module 2000 is modular, for example, and can be manufactured and sold as an electromechanical integrated motor with a motor, sensors, drives, and controller.
The power conversion device 1000 can convert power from the power source 101 (see fig. 2) into power to be supplied to the motor 200. The power conversion device 1000 is connected to the motor 200. For example, the power conversion device 1000 can convert dc power into three-phase ac power that is analog sine waves of a phase, B phase, and C phase. In this specification, "connection" of components (constituent elements) to each other mainly means electrical connection.
The motor 200 is, for example, a three-phase ac motor. The motor 200 has an a-phase coil M1, a B-phase coil M2, and a C-phase coil M3, and is connected to the 1 st inverter 120 and the 2 nd inverter 130 of the inverter unit 100. Specifically, the 1 st inverter 120 is connected to one end of each phase coil of the motor 200, and the 2 nd inverter 130 is connected to the other end of each phase coil.
The control circuit 300 includes, for example, a power supply circuit 310, an angle sensor 320, an input circuit 330, a controller 340, a drive circuit 350, and a ROM 360. The components of the control circuit 300 are mounted on, for example, 1 circuit board (typically, a printed circuit board). The control circuit 300 is connected to the inverter unit 100, and controls the inverter unit 100 based on input signals from the current sensor 150 and the angle sensor 320. Examples of control methods include vector control, Pulse Width Modulation (PWM), and Direct Torque Control (DTC). However, depending on the motor control method (e.g., sensorless control), the angle sensor 320 may not be necessary.
The control circuit 300 can control the position, the rotation speed, the current, and the like of the target rotor of the motor 200 to realize closed-loop control. In addition, the control circuit 300 may include a torque sensor instead of the angle sensor 320. In this case, the control circuit 300 can control the target motor torque.
The power supply circuit 310 generates a power supply voltage (e.g., 3V or 5V) necessary for each block in the circuit from the voltage of the power supply 101, e.g., 12V.
The angle sensor 320 is, for example, a resolver (レゾルバ) or a hall IC. Alternatively, the angle sensor 320 is also realized by a combination of a sensor magnet and an MR sensor having a Magnetoresistive (MR) element. The angle sensor 320 detects a rotation angle of the rotor (hereinafter referred to as a "rotation signal"), and outputs the rotation signal to the controller 340.
The input circuit 330 receives a phase current (hereinafter, sometimes referred to as "actual current") detected by the current sensor 150, converts the level of the actual current to an input level of the controller 340 as necessary, and outputs the actual current to the controller 340. The input circuit 330 is, for example, an analog-digital conversion circuit.
The controller 340 is an integrated circuit that controls the entire power conversion device 1000, and is, for example, a microcontroller or an FPGA (Field Programmable Gate Array). The controller 340 controls the switching operation (on or off) of each switching element (typically, a semiconductor switching element) in the 1 st and 2 nd inverters 120 and 130 of the inverter unit 100. The controller 340 sets a target current value in accordance with an actual current value, a rotor rotation signal, and the like, generates a PWM signal, and outputs the PWM signal to the drive circuit 350.
The driving circuit 350 is representatively a pre-driver (also sometimes referred to as a "gate driver"). The drive circuit 350 generates a control signal (gate control signal) for controlling the switching operation of each switching element in the 1 st and 2 nd inverters 120 and 130 of the inverter unit 100 in accordance with the PWM signal, and supplies the control signal to the gate of each switching element. When the driving target is a motor that can be driven by a low voltage, a predriver may not be necessary. In this case, the function of the pre-driver can be installed in the controller 340.
The driving circuit 350 has a voltage detection circuit 380. The voltage detection circuit 380 detects voltages applied to a plurality of switching elements included in the 1 st and 2 nd inverters 120 and 130, respectively, for example. For example, when the switching elements are FETs, the voltage detection circuit 380 detects the source-drain voltage of each FET.
The ROM360 is, for example, a writable memory (e.g., PROM), a rewritable memory (e.g., flash memory), or a read-only memory. The ROM360 stores a control program including a command set for causing the controller 340 to control the power conversion apparatus 1000. For example, the control program is temporarily loaded into a RAM (not shown) at the time of startup.
A specific circuit configuration of the inverter unit 100 will be described with reference to fig. 2.
Fig. 2 schematically shows a circuit configuration of the inverter unit 100 of the present embodiment.
The power supply 101 generates a predetermined power supply voltage (for example, 12V). As the power source 101, for example, a dc power source is used. However, the power source 101 may be an AC-DC converter or a DC-DC converter, or may be a battery (secondary battery). As shown, the power source 101 may be a single power source shared by the 1 st and 2 nd inverters 120 and 130, or may include a1 st power source (not shown) for the 1 st inverter 120 and a2 nd power source (not shown) for the 2 nd inverter 130.
Fuses ISW _11 and ISW _12 are connected between power supply 101 and 1 st inverter 120. Fuses ISW _11 and ISW _12 can cut off a large current that can flow from power supply 101 to 1 st inverter 120. Fuses ISW _21 and ISW _22 are connected between power supply 101 and 2 nd inverter 130. Fuses ISW _21 and ISW _22 can cut off a large current that can flow from power supply 101 to 2 nd inverter 130. Instead of the fuse, a relay or the like may be used.
Although not shown, coils are provided between the power source 101 and the 1 st inverter 120 and between the power source 101 and the 2 nd inverter 130. The coil functions as a noise filter for smoothing high-frequency noise included in the voltage waveform supplied to each inverter or high-frequency noise generated in each inverter so as not to flow out to the power source 101 side. A capacitor is connected to a power supply terminal of each inverter. The capacitor is a so-called bypass capacitor, suppressing voltage ripple (リプル). The capacitor is, for example, an electrolytic capacitor, and the capacity and the number used are appropriately determined by design specifications and the like.
The 1 st inverter 120 has a bridge circuit composed of 3 legs. Each branch has a high-side switching element, a low-side switching element, and a shunt resistor. The phase a branch has a high-side switching element SW _ A1H, a low-side switching element SW _ A1L, and A1 st shunt resistor S _ A1. The phase-B branch has a high-side switching element SW _ B1H, a low-side switching element SW _ B1L, and a1 st shunt resistor S _ B1. The C-phase branch has a high-side switching element SW _ C1H, a low-side switching element SW _ C1L, and a1 st shunt resistor S _ C1.
As the switching element, for example, a combination of a field effect transistor (typically MOSFET) or an Insulated Gate Bipolar Transistor (IGBT) in which a parasitic diode is formed and a free wheeling diode connected in parallel thereto can be used.
The 1 st shunt resistor S _ A1 is used to detect the a-phase current IA1 flowing through the a-phase coil M1, and is connected between the low-side switching element SW _ A1L and the GND line GL, for example. The 1 st shunt resistor S _ B1 is used to detect the B-phase current IB1 flowing through the B-phase coil M2, and is connected between the low-side switching element SW _ B1L and the GND line GL, for example. The 1 st shunt resistor S _ C1 is used to detect the C-phase current IC1 flowing through the C-phase coil M3, and is connected between the low-side switching element SW _ C1L and the GND line GL, for example. The 3 shunt resistors S _ a1, S _ B1, and S _ C1 are connected to the GND line GL of the 1 st inverter 120.
The 2 nd inverter 130 has a bridge circuit composed of 3 legs. Each branch has a high-side switching device, a low-side switching device, and a shunt resistor. The a-phase branch has a high-side switching element SW _ A2H, a low-side switching element SW _ A2L, and a shunt resistor S _ A2. The phase B branch has a high-side switching element SW _ B2H, a low-side switching element SW _ B2L, and a shunt resistor S _ B2. The C-phase branch has a high-side switching element SW _ C2H, a low-side switching element SW _ C2L, and a shunt resistor S _ C2.
The shunt resistor S _ A2 is used to detect the a-phase current IA2, and is connected between the low-side switching element SW _ A2L and the GND line GL, for example. The shunt resistor S _ B2 is used to detect the B-phase current IB2, and is connected between the low-side switching element SW _ B2L and the GND line GL, for example. The shunt resistor S _ C2 is used for detecting the C-phase current IC2, and is connected between the low-side switching element SW _ C2L and the GND line GL, for example. The 3 shunt resistors S _ a2, S _ B2, and S _ C2 are all connected to the GND line GL of the 2 nd inverter 130.
The current sensor 150 includes, for example, shunt resistors S _ a1, S _ B1, S _ C1, S _ a2, S _ B2, and S _ C2, and a current detection circuit (not shown) that detects a current flowing through each shunt resistor.
The a-phase branch of the 1 st inverter 120 (specifically, the node between the high-side switching element SW _ A1H and the low-side switching element SW _ A1L) is connected to one end A1 of the a-phase coil M1 of the motor 200, and the a-phase branch of the 2 nd inverter 130 is connected to the other end a2 of the a-phase coil M1. The B-phase branch of the 1 st inverter 120 is connected to one end B1 of a B-phase coil M2 of the motor 200, and the B-phase branch of the 2 nd inverter 130 is connected to the other end B2 of the coil M2. The C-phase branch of the 1 st inverter 120 is connected to one end C1 of a C-phase coil M3 of the motor 200, and the C-phase branch of the 2 nd inverter 130 is connected to the other end C2 of the coil M3.
Control circuit 300 drives motor 200 by performing three-phase energization control using both 1 st and 2 nd inverters 120 and 130. Specifically, the control circuit 300 performs three-phase energization control by performing switching control of the switching elements of the 1 st inverter 110 and the switching elements of the 2 nd inverter 140 with mutually opposite phases (phase difference of 180 °). At this time, fuses ISW _11, ISW _12, ISW _21, and ISW _22 are turned on. For example, focusing on the H-bridge including the switching elements SW _ A1L, SW _ A1H, SW _ A2L, and SW _ A2H, the switching element SW _ A2L is turned off when the switching element SW _ A1L is turned on, and the switching element SW _ A2L is turned on when the switching element SW _ A1L is turned off. Similarly, when the switching element SW _ A1H is turned on, the switching element SW _ A2H is turned off, and when the switching element SW _ A1H is turned off, the switching element SW _ A2H is turned on. The current output from the power supply 101 flows to the GND line GL through the high-side switching element, the coil, and the low-side switching element. The wiring of the power conversion apparatus 100 is sometimes referred to as open wiring.
Here, an example of a path of a current flowing through the a-phase coil M1 will be described. When the switching element SW _ A1H and the switching element SW _ A2L are turned on and the switching element SW _ A2H and the switching element SW _ A1L are turned off, a current flows through the power source 101, the switching element SW _ A1H, the coil M1, the switching element SW _ A2L, and the GND line GL in this order. When the switching element SW _ A2H and the switching element SW _ A1L are turned on and the switching element SW _ A1H and the switching element SW _ A2L are turned off, a current flows in order through the power source 101, the switching element SW _ A2H, the coil M1, the switching element SW _ A1L, and the GND line GL.
In addition, a part of the current flowing from the switching element SW _ A1H to the coil M1 may flow to the switching element SW _ A2H. That is, the current flowing from the switching element SW _ A1H to the coil M1 may flow while branching off to the switching element SW _ A2L and the switching element SW _ A2H. Similarly, a part of the current flowing from the switching element SW _ A2H to the coil M1 may flow to the switching element SW _ A1H.
Next, an example of a path of a current flowing through the B-phase coil M2 will be described. When the switching element SW _ B1H and the switching element SW _ B2L are turned on and the switching element SW _ B2H and the switching element SW _ B1L are turned off, a current flows in order through the power source 101, the switching element SW _ B1H, the coil M2, the switching element SW _ B2L, and the GND line GL. When the switching element SW _ B2H and the switching element SW _ B1L are turned on and the switching element SW _ B1H and the switching element SW _ B2L are turned off, a current flows through the power source 101, the switching element SW _ B2H, the coil M2, the switching element SW _ B1L, and the GND line GL in this order.
In addition, as described above, a part of the current flowing from the switching element SW _ B1H to the coil M2 may flow to the switching element SW _ B2H. Part of the current flowing from the switching element SW _ B2H to the coil M2 may flow to the switching element SW _ B1H.
Next, an example of a path of a current flowing through the C-phase coil M3 will be described. When the switching element SW _ C1H and the switching element SW _ C2L are turned on and the switching element SW _ C2H and the switching element SW _ C1L are turned off, a current flows in order through the power source 101, the switching element SW _ C1H, the coil M3, the switching element SW _ C2L, and the GND line GL. When the switching element SW _ C2H and the switching element SW _ C1L are turned on and the switching element SW _ C1H and the switching element SW _ C2L are turned off, a current flows through the power source 101, the switching element SW _ C2H, the coil M3, the switching element SW _ C1L, and the GND line GL in this order.
In addition, as described above, a part of the current flowing from the switching element SW _ C1H to the coil M3 may flow to the switching element SW _ C2H. Part of the current flowing from the switching element SW _ C2H to the coil M3 may flow to the switching element SW _ C1H.
Fig. 3 illustrates a current waveform (sine wave) obtained by plotting current values flowing through the coils of the a-phase, the B-phase, and the C-phase of the motor 200 when the inverter unit 100 is controlled in accordance with the three-phase energization control. The horizontal axis represents the motor electrical angle (deg) and the vertical axis represents the current value (A). In the current waveform of fig. 3, the current value is plotted per 30 ° electrical angle. I ispkThe maximum current value (peak current value) of each phase is shown. For example, the control circuit 300 can generate a PWM signal for obtaining the current waveform shown in fig. 3.
[ 2. Fault diagnosis ]
Next, the failure diagnosis method of the present embodiment will be described. Here, a method of diagnosing whether or not a switching element is malfunctioning will be described by taking the power conversion apparatus 1000 shown in fig. 1 as an example.
In the case where the switching element is an FET, the failures are roughly classified into an "open failure" and a "short failure". The "open failure" refers to a failure in which the source-drain of the FET is open (in other words, the resistance between the source and the drain always becomes high impedance). "short-circuit fault" refers to a fault in which the source-drain of the FET is always short-circuited. In the failure diagnosis of the present embodiment, an open failure of the switching element is detected.
The algorithm for implementing the failure diagnosis method according to the present embodiment can be implemented by hardware such as a microcontroller, an Application Specific Integrated Circuit (ASIC), or an FPGA, or can be implemented by a combination of hardware and software.
Fig. 4 illustrates functional blocks of the controller 340 for performing overall motor control. Fig. 5 is a flowchart showing an example of the failure diagnosis performed by the controller 340.
In this specification, each block in the functional block diagram is expressed in a functional block unit, not in a hardware unit. The software for motor control and failure diagnosis may be, for example, a module constituting a computer program for executing specific processing corresponding to each functional block. Such a computer program is stored in the ROM360, for example. The controller 340 can read out commands from the ROM360 and successively execute respective processes.
The controller 340 receives the current value detected by the current sensor 150 via the input circuit 330 (fig. 1). The current sensor 150 detects the current flowing through each phase by using the shunt resistor, and can determine the currents flowing through the plurality of switching elements included in the 1 st and 2 nd inverters 120 and 130, respectively. The voltage detection circuit 380 (fig. 1) detects voltages applied to the plurality of switching elements included in the 1 st and 2 nd inverters 120 and 130, respectively, for example, and outputs the detected voltages to the controller 340.
The controller 340 includes, for example, a failure diagnosis unit 800 and a motor control unit 900. The fault diagnosis unit 800 diagnoses the presence or absence of a fault using information of current and/or voltage associated with each of the plurality of switching elements. The failure diagnosis unit 800 outputs a signal indicating the diagnosis result of the presence or absence of a failure to the motor control unit 900.
The motor control unit 900 generates a PWM signal for controlling the entire switching operation of the switching elements of the 1 st and 2 nd inverters 120 and 130 by using, for example, vector control, based on the diagnosis result. The motor control unit 900 outputs the PWM signal to the driving circuit 350.
The motor control unit 900 switches control of the 1 st and 2 nd inverters 120 and 130 according to the diagnosis result. Specifically, the motor control unit 900 can determine the on/off operation of the switching elements of the 1 st and 2 nd inverters 120 and 130 based on the diagnosis result. The motor control unit 900 can also determine on/off operations of the fuses ISW _11, ISW _12, ISW _21, and ISW _22 based on the diagnosis result.
In this specification, for convenience of description, each functional block may be referred to as a unit. Of course, this notation is not intended to be construed restrictively as hardware or software for each functional block.
In the case where each functional block is installed as software in the controller 340, the execution subject of the software may be, for example, the core of the controller 340. As described above, the controller 340 can be implemented by an FPGA. In this case, all or a part of the functional blocks can be realized by hardware.
By distributing the processing using a plurality of FPGAs, the computational load of a specific computer can be distributed. In this case, all or a part of the illustrated functional blocks can be distributed and mounted on a plurality of FPGAs. The FPGAs are connected to communicate with each other via a Control Area Network (CAN) mounted on the vehicle, for example, and CAN transmit and receive data.
When the plurality of switching elements included in the 1 st and 2 nd inverters 120 and 130 are not malfunctioning, the control circuit 300 executes the three-phase energization control described above as a control mode in a normal state. In the three-phase energization control, the plurality of switching elements are repeatedly switched on and off. The failure diagnosis unit 800 performs failure diagnosis of the present embodiment on the 12 switching elements SW _ A1H, SW _ A1L, SW _ B1H, SW _ B1L, SW _ C1H, SW _ C1L, SW _ A2H, SW _ A2L, SW _ B2H, SW _ B2L, SW _ C2H, and SW _ C2L included in the 1 st and 2 nd inverters 120 and 130, respectively.
[ 2-1. Fault diagnosis of switching element Using Current value ]
The operation of detecting the current flowing through the switching element to diagnose whether or not the switching element has a failure will be described with reference to fig. 5. When the switching element is an FET, a current flowing through the switching element is a current flowing between the source and the drain of the FET. Here, the failure diagnosis unit 800 that diagnoses the presence or absence of a failure of the switching element by the value of the current flowing through the switching element is expressed as a failure diagnosis unit 800_ I.
Here, an example of diagnosing the presence or absence of a failure in the switching element SW _ A1H will be described, where the switching element SW _ A1H is 1 of the plurality of switching elements included in the 1 st and 2 nd inverters 120 and 130. This failure diagnosis can be repeatedly performed every time the operation of turning on the switching element SW _ A1H is performed.
The fault diagnosis unit 800_ I detects a current flowing in the switching element SW _ A1H when the switching element SW _ A1H is controlled to the on state (step S101). For example, when the switching element SW _ A1H and the switching element SW _ A2L are turned on and the switching element SW _ A2H and the switching element SW _ A1L are turned off, a current flows through the power source 101, the switching element SW _ A1H, the coil M1, the switching element SW _ A2L, the shunt resistor S _ A2, and the GND line GL in this order. The magnitude of the current flowing through the shunt resistor S _ a2 corresponds to the magnitude of the current flowing through the switching element SW _ A1H. The failure diagnosis unit 800_ I can detect the magnitude of the current flowing through the switching element SW _ A1H from the current flowing through the shunt resistor S _ a2, for example.
Next, the failure diagnosis unit 800_ I determines whether or not the current flowing through the switching element SW _ A1H is smaller than a predetermined current when the switching element SW _ A1H is controlled to the on state (step S102). The prescribed current is, for example, 10 mA. In addition, 10mA is an example, and the embodiment of the present disclosure is not limited thereto.
In this example, if the switching element SW _ A1H is not failed, that is, normal, a current of 10mA or more flows through the switching element SW _ A1H to which the gate control signal is supplied. When the open failure occurs in the switching element SW _ A1H, the current flowing through the switching element SW _ A1H to which the gate control signal is supplied is less than 10 mA.
When it is determined that the detected current is not less than 10mA, failure diagnosis unit 800_ I determines that switching element SW _ A1H is normal (step S108). The failure diagnosis unit 800_ I outputs a signal indicating that the switching element SW _ A1H is normal to the motor control unit 900, and returns to the processing of step S101.
If it is determined in step S102 that the detected current is less than 10mA, the process proceeds to step S103. In step S103, the fault diagnosis unit 800_ I detects a time when the current flowing in the switching element SW _ A1H is less than 10mA when the switching element SW _ A1H is controlled to the on state. Next, failure diagnosis section 800_ I determines whether or not the detected time is equal to or longer than a predetermined time (step S104). The predetermined time is, for example, 50. mu.s. In addition, 50 μ s is an example, and the embodiment of the present disclosure is not limited thereto. The predetermined time can be set according to the structure and the rotation speed of the motor 200.
Even when the switching element SW _ A1H is normal, a current flowing through the switching element SW _ A1H in an on state may be less than 10mA in a short time due to interference of noise or the like. If it is determined that the switching element SW _ A1H is abnormal based on an abnormal value due to such noise, accurate determination cannot be made. Therefore, in the present embodiment, when the time during which the current is less than 10mA is short (for example, less than 50 μ s), it is determined that the switching element SW _ A1H is normal.
When failure diagnosis unit 800_ I determines that the detected time is not 50 μ S or more, it determines that switching element SW _ A1H is normal (step S108). The failure diagnosis unit 800_ I outputs a signal indicating that the switching element SW _ A1H is normal to the motor control unit 900, and returns to the processing of step S101.
If it is determined in step S104 that the detected time is 50 μ S or more, the process proceeds to step S105. In step S105, the failure diagnosis unit 800_ I counts the number of times the detected time is 50 μ S or more. Next, failure diagnosis section 800_ I determines whether or not the counted total number of times is equal to or greater than a predetermined number of times (step S106). The predetermined number of times is, for example, 3 times. The 3 times are examples, and the embodiments of the present disclosure are not limited to these. The number of times may be 2 or 4 or more as long as the predetermined number of times is plural.
When the detected time is 50 μ s or more, there is a possibility that the open failure occurs in the switching element SW _ A1H, but it is not determined as a failure at the stage of detecting the case only 1 time. When the open failure of the switching element SW _ A1H has actually occurred, the control circuit 300 determines that the detected time is 50 μ S or more in the processing of step S104 every time the gate control signal is supplied to the switching element SW _ A1H. When it is determined that the time detected a plurality of times (for example, 3 times) is 50 μ s or more, it is determined that the open failure has occurred in the switching element SW _ A1H.
If it is determined in step S106 that the counted total number of times is not 3 or more times, failure diagnosis unit 800_ I determines that switching element SW _ A1H is normal (step S108). The failure diagnosis unit 800_ I outputs a signal indicating that the switching element SW _ A1H is normal to the motor control unit 900, and returns to the processing of step S101.
When it is determined in step S106 that the counted total number of times is 3 or more, it is determined that the open failure has occurred in the switching element SW _ A1H (step S107). The failure diagnosis unit 800_ I outputs a signal indicating that the switching element SW _ A1H has failed to the motor control unit 900. The failure diagnosis unit 800_ I may output a signal indicating that the switching element SW _ A1H has failed to the motor control unit 900, and then return to the process of step S101.
Upon receiving a signal indicating that the switching element SW _ A1H has failed, the motor control unit 900 changes the control mode of the motor 200 from the normal control mode to the abnormal control mode.
The control mode in the abnormal state is, for example, a control mode in which the motor 200 is driven by the inverter that has not failed at the neutral point of the inverter-constituting coil that has failed. When the switching element SW _ A1H fails, the motor control unit 900 performs control to open the fuses ISW _11 and ISW _ 12. Thereby, the 1 st inverter 120 having the failed switching element SW _ A1H is separated from the power supply and GND. Then, for example, switching elements SW _ A1H, SW _ B1H, and SW _ C1H are turned off, and switching elements SW _ A1L, SW _ B1L, and SW _ C1L are turned on, thereby forming a neutral point in inverter 1 120. By using this neutral point, the motor 200 can be driven by the 2 nd inverter 130 in which no failure has occurred.
The control mode in the abnormal state may be two-phase energization control. When the switching element SW _ A1H belonging to the a-phase fails, the motor control unit 900 turns off all the switching elements SW _ A1H, SW _ A1L, SW _ A2H, and SW _ A2L belonging to the a-phase. Then, two-phase energization control is performed using switching elements SW _ B1H, SW _ B1L, SW _ B2H, SW _ B2L, SW _ C1H, SW _ C1L, SW _ C2H, and SW _ C2L belonging to the B-phase and the C-phase. In this way, the motor 200 can be driven using the phase that has not failed.
The control mode in the abnormal state may be off. The shutdown is control for stopping the operation of the motor 200.
The failure diagnosis unit 800_ I also performs the same failure diagnosis as that for the switching element SW _ A1H described above for the switching elements other than the switching element SW _ A1H among the plurality of switching elements included in the 1 st and 2 nd inverters 120 and 130.
In the failure diagnosis of the present embodiment, when a failure occurs in a switching element, which switching element of a plurality of switching elements has failed can be determined. By being able to specify the switching element in which the failure has occurred, appropriate control according to the failure location can be performed.
Next, an example of an operation for detecting a current flowing through the detected switching element and diagnosing whether or not the switching element has a failure will be described with reference to fig. 6.
The failure diagnosis unit 800_ I shown in fig. 6 is a failure diagnosis unit 800 that diagnoses the presence or absence of a failure of the switching element using the value of the current flowing through the detected switching element. Here, an example of diagnosing the presence or absence of a failure in the switching element SW _ A1H, which is 1 of the plurality of switching elements included in the 1 st and 2 nd inverters 120 and 130, will be described.
The detected current value ("I" in fig. 6) of the switching element SW _ A1H is input to the failure diagnosis unit 800_ I. Also, the gate control signal ("S" in fig. 6) that turns on the switching element SW _ A1H is input to the failure diagnosis unit 800_ I. The absolute value block 811 finds the absolute value of the detected current of the switching element SW _ A1H. The Comparator (Comparator)812 compares the obtained absolute value with a predetermined lower current limit value. This lower limit current value is 10mA, for example, corresponding to the predetermined current used in the processing of step S102 shown in fig. 5. In addition, 10mA is an example, and the embodiment of the present disclosure is not limited thereto.
The comparator 812 outputs 1 when the absolute value of the current is 10mA or more, and outputs 0 when the absolute value of the current is less than 10 mA. The NOT block 821 inverts the output value of the comparator 812 by performing a logical operation of "NOT".
The output value of the NOT block 821 AND the gate control signal are input to the AND block 822. Here, the High-level gate control signal for turning on the switching element SW _ A1H is set to 1, and the Low-level gate control signal for turning off the switching element SW _ A1H is set to 0. The AND block 822 performs a logical operation of AND. When both the output value of the NOT block 821 AND the gate control signal are 1, the AND block 822 outputs 1. That is, the AND block 822 outputs 1 when the current flowing in the switching element SW _ A1H is smaller than the lower limit value when the switching element SW _ A1H is controlled to the on state. Otherwise, the AND block 822 outputs 0.
The output value of the AND block 822 AND the output value of the comparator 841 are input to an OR block 832. The OR block 832 performs a logical operation of "OR". The initial value output by the comparator 841 is 0. OR block 832 outputs 1 when at least one of the output value of AND block 822 AND the output value of comparator 841 is 1. When both the output value of the AND block 822 AND the output value of the comparator 841 are 0, the OR block 832 outputs 0. The NOT block 833 performs a logical operation of "NOT" to invert the output value of the OR block 832.
An Integrator (Integrator)831 accumulates the output value of the AND block 822 to output. The comparator 841 compares the output value of the integrator 831 with the 1 st reference value. The comparator 851 compares the output value of the integrator 831 with a2 nd reference value.
Fig. 7 is a diagram showing the relationship among the output value of the AND block 822, the output value of the integrator 831, AND the output value of the comparator 841. The horizontal axis of fig. 7 represents time. The 1 st reference value is a value corresponding to a predetermined time used in the processing of step S104 shown in fig. 5. For example, the output value of the integrator 831 corresponding to a predetermined time 50 μ s is set to 10. When the integrator 831 is hardware or the like, if the output value of the integrator 831 is represented by a voltage, the output value "10" corresponds to, for example, 1.0V, which is the output voltage of the integrator 831.
As described above, even when the switching element SW _ A1H is normal, a current flowing through the switching element SW _ A1H in an on state may be less than 10mA in a short time due to interference of noise or the like. In the example of fig. 7, the portion of time that the AND block 822 outputs 1 for 10 μ s corresponds to noise. The integrator 831 outputs a value obtained by accumulating the output values of the AND block 822 for a period of 10 μ s. In the example of fig. 7, the integrator 831 outputs 2. Since the output value "2" of the integrator 831 is smaller than the 1 st reference value "10", the comparator 841 outputs 0.
If the switching element SW _ A1H is turned off, the AND block 822 outputs 0. When both the output value of the AND block 822 AND the output value of the comparator 841 are 0, the OR block 832 outputs 0. Accordingly, NOT block 833 outputs a 1. If a1 is input from the NOT block 833, the integrator 831 resets the accumulated value.
On the other hand, if the time for which the AND block 822 outputs 1 is 50 μ s or more, the integrator 831 performs accumulation AND outputs a value of 10 or more. Since the output value of the integrator 831 is equal to or greater than the 1 st reference value "10", the comparator 841 outputs 1.
With the output value of the comparator 841 being 1, even if the switching element SW _ A1H is turned off, the OR block 832 outputs 1, and the NOT block 833 also outputs 0. If 0 is input from the NOT block 833, the integrator 831 continues accumulation while keeping the accumulated value. No resetting of the accumulation value is performed.
Fig. 8 is a diagram showing the relationship among the output value of the AND block 822, the output value of the integrator 831, AND the output value of the comparator 851. The horizontal axis of fig. 8 represents time. The 2 nd reference value is a value corresponding to the predetermined number of times used in the processing of step S106 shown in fig. 5. For example, the output value of the integrator 831 corresponding to the number of counts 3 is set to 30.
In the case where the output value of the comparator 841 is 1, the integrator 831 continues to accumulate the output value of the AND block 822. The comparator 851 outputs 0 during a period in which the output value of the integrator 831 is less than the 2 nd reference value "30". When the output value of the integrator 831 is equal to or greater than the 2 nd reference value "30", the comparator 851 outputs 1. The output value "1" of the comparator 851 becomes a signal indicating that the switching element SW _ A1H is failed, and is input to the motor control unit 900.
The comparator 851 outputs 0 during a period in which the output value of the integrator 831 is less than the 2 nd reference value "30". The output value "0" of the comparator 851 becomes a signal indicating that the switching element SW _ A1H is normal, and is input to the motor control unit 900.
In addition, when the output value of the integrator 831 is smaller than the 2 nd reference value "30" even after a certain time (for example, several seconds) elapses after the output value of the comparator 841 becomes 1, the integrator 831 may reset the accumulated value. When the AND block 822 outputs 1 for 50 μ s or more, the switching element SW _ A1H may malfunction. However, when the AND block 822 does not output 1 for 50 μ s or more continuously, it may be considered that the switching element SW _ A1H has not failed, AND the integrator 831 is reset to continue the failure diagnosis.
In this way, the fault diagnosis unit 800_ I can diagnose whether or not the switching element is faulty using the value of the current flowing through the detected switching element.
The failure diagnosis unit 800_ I also performs the same failure diagnosis as that for the switching element SW _ A1H described above for the switching elements other than the switching element SW _ A1H among the plurality of switching elements included in the 1 st and 2 nd inverters 120 and 130.
In the failure diagnosis of the present embodiment, when a failure occurs in a switching element, it is possible to determine which switching element among a plurality of switching elements has failed. Since the switching element having a failure can be specified, appropriate control can be performed according to the failure location.
[ 2-2. Fault diagnosis of switching element Using Voltage value ]
Next, an operation of detecting a voltage applied to the switching element to diagnose whether or not the switching element has a failure will be described with reference to fig. 9. Here, the failure diagnosis unit 800 that diagnoses the presence or absence of a failure of the switching element by the value of the voltage applied to the switching element is expressed as failure diagnosis unit 800_ V. Fig. 9 is a flowchart showing an operation of diagnosing the presence or absence of a failure of the switching element by using the value of the voltage applied to the switching element. In the case where the switching element is an FET, the voltage applied to the switching element is a source-drain voltage of the FET. The operations of steps S105 to S108 shown in fig. 9 are the same as the operations of steps S105 to S108 shown in fig. 5.
Here, an example of diagnosing the presence or absence of a failure in the switching element SW _ A1H will be described, where the switching element SW _ A1H is 1 of the plurality of switching elements included in the 1 st and 2 nd inverters 120 and 130. This failure diagnosis can be repeatedly performed every time the operation of turning on the switching element SW _ A1H is performed.
The failure diagnosis unit 800_ V detects the source-drain voltage of the switching element SW _ A1H when the switching element SW _ A1H is controlled to the on state (step S111). For example, the fault diagnosis unit 800_ V can detect the source-drain voltage of the switching element SW _ A1H using the output signal of the voltage detection circuit 380 (fig. 1).
Next, the failure diagnosis unit 800_ V determines whether or not the source-drain voltage of the switching element SW _ A1H is equal to or higher than a predetermined voltage when the switching element SW _ A1H is controlled to be in the on state (step S112). The predetermined voltage is, for example, 0.5V. In addition, 0.5V is an example, and the embodiment of the present disclosure is not limited thereto.
In this example, when the switching element SW _ A1H is not failed, that is, is normal, the source-drain voltage of the switching element SW _ A1H to which the gate control signal is supplied is less than 0.5V. When the switching element SW _ A1H has an open-circuit fault, the source-drain voltage of the switching element SW _ A1H to which the gate control signal is supplied is 0.5V or more.
When it is determined that the detected voltage is not 0.5V or more, failure diagnosis section 800_ V determines that switching element SW _ A1H is normal (step S108). The failure diagnosis unit 800_ V outputs a signal indicating that the switching element SW _ A1H is normal to the motor control unit 900, and returns to the process of step S111.
If it is determined in step S112 that the detected voltage is 0.5V or more, the process proceeds to step S113. In step S113, the failure diagnosis unit 800_ V detects a time when the source-drain voltage of the switching element SW _ A1H is 0.5V or more when the switching element SW _ A1H is controlled to the on state. Next, failure diagnosis section 800_ V determines whether or not the detected time is equal to or longer than a predetermined time (step S114). The predetermined time is, for example, 50. mu.s. In addition, 50 μ s is an example, and the embodiment of the present disclosure is not limited thereto.
Even when the switching element SW _ A1H is normal, there is a possibility that the source-drain voltage of the switching element SW _ A1H, which is turned on for a short time due to interference of noise or the like, is 0.5V or more. If it is determined that the switching element SW _ A1H is abnormal based on an abnormal value due to such noise, accurate determination cannot be made. Therefore, in the present embodiment, when the time during which the voltage is 0.5V or more is short (for example, less than 50 μ s), it is determined that the switching element SW _ A1H is normal.
When it is determined that the detected time is not 50 μ S or more, failure diagnosis section 800_ V determines that switching element SW _ A1H is normal (step S108). The failure diagnosis unit 800_ V outputs a signal indicating that the switching element SW _ A1H is normal to the motor control unit 900, and returns to the process of step S111.
If it is determined in step S114 that the detected time is 50 μ S or more, the process proceeds to step S105. Since the operations of steps S105 to S108 shown in fig. 9 are the same as those of steps S105 to S108 shown in fig. 5, repetition of detailed description thereof will be omitted here.
In the example of fig. 9, when it is determined in step S108 that the switching element SW _ A1H is normal, the failure diagnosis unit 800_ V outputs a signal indicating that the switching element SW _ A1H is normal to the motor control unit 900, and returns to the processing of step S111. When it is determined in step S107 that the open failure has occurred in the switching element SW _ A1H, the failure diagnosis unit 800_ V outputs a signal indicating that the switching element SW _ A1H has failed to the motor control unit 900. The failure diagnosis unit 800_ I may output a signal indicating that the switching element SW _ A1H has failed to the motor control unit 900, and then return to the process of step S111.
Upon receiving a signal indicating that the switching element SW _ A1H has failed, the motor control unit 900 changes the control mode of the motor 200 from the normal control mode to the abnormal control mode.
The failure diagnosis unit 800_ V also performs the same failure diagnosis as that for the switching element SW _ A1H described above for the switching elements other than the switching element SW _ A1H among the plurality of switching elements included in the 1 st and 2 nd inverters 120 and 130.
In the failure diagnosis of the present embodiment, when a failure occurs in a switching element, which switching element of a plurality of switching elements has failed can be determined. Since the switching element having a failure can be specified, appropriate control can be performed according to the failure location.
Next, an example of an operation for detecting a voltage applied to the switching element and diagnosing whether or not the switching element has a failure will be described with reference to fig. 10.
The failure diagnosis unit 800_ V shown in fig. 10 is a failure diagnosis unit 800 that diagnoses the presence or absence of a failure of the switching element using the detected value of the voltage applied to the switching element. Here, an example of diagnosing the presence or absence of a failure in the switching element SW _ A1H will be described, where the switching element SW _ A1H is 1 of the plurality of switching elements included in the 1 st and 2 nd inverters 120 and 130.
The detected source-drain voltage ("V" in fig. 10) of the switching element SW _ A1H is input to the failure diagnosis unit 800_ V. Then, a gate control signal (yes in fig. 10) that turns on the switching element SW _ A1H is input to the failure diagnosis unit 800_ V. The absolute value block 813 finds the absolute value of the source-drain voltage of the detected switching element SW _ A1H. The comparator 814 compares the obtained absolute value with a predetermined lower voltage limit value. This lower limit voltage value is equal to the predetermined voltage used in the processing of step S112 shown in fig. 9, and is, for example, 0.5V. In addition, 0.5V is an example, and the embodiment of the present disclosure is not limited thereto.
The comparator 814 outputs 1 when the absolute value of the voltage is 0.5V or more, and outputs 0 when the absolute value of the voltage is less than 0.5V. The output of the comparator 814 AND the gate control signal are input to an AND block 822. The AND block 822 outputs 1 when both the output value of the comparator 814 AND the gate control signal are 1. That is, when the source-drain voltage of the switching element SW _ A1H when the switching element SW _ A1H is controlled to be in the on state is equal to or higher than the lower limit value, the AND block 822 outputs 1. Otherwise, the AND block 822 outputs 0. The output of the AND block 822 is input to an integrator 831 AND an OR block 832.
The operations of the integrator 831, OR block 832, NOT block 833, comparator 841, and comparator 851 are the same as those described with reference to fig. 6 to 8, and therefore, repetition of detailed description thereof is omitted here.
In the case where the output value of the comparator 841 is 1, the integrator 831 continues to accumulate the output value of the AND block 822. The comparator 851 outputs 0 during a period in which the output value of the integrator 831 is less than the 2 nd reference value "30". When the output value of the integrator 831 is equal to or greater than the 2 nd reference value "30", the comparator 851 outputs 1.
In this way, the failure diagnosis unit 800_ V can diagnose the presence or absence of a failure of the switching element using the detected value of the voltage applied to the switching element.
The failure diagnosis unit 800_ V also performs the same failure diagnosis as that for the switching element SW _ A1H described above for the switching elements other than the switching element SW _ A1H among the plurality of switching elements included in the 1 st and 2 nd inverters 120 and 130.
In the failure diagnosis of the present embodiment, when a failure occurs in a switching element, which switching element of a plurality of switching elements has failed can be determined. Since the switching element having a failure can be specified, appropriate control can be performed according to the failure location.
[ 2-3 ] Fault diagnosis of switching element Using both Current value and Voltage value ]
Next, an operation of diagnosing whether or not a failure occurs in the switching element using both the value of the current flowing through the switching element and the value of the voltage applied to the switching element will be described. In this example, as shown in fig. 11, the controller 340 has a failure diagnosis unit 800_ IV as the failure diagnosis unit 800. The failure diagnosis unit 800_ IV diagnoses the presence or absence of a failure of the switching element using both the value of the current flowing through the switching element and the value of the voltage applied to the switching element.
Fig. 12 shows an example of a functional block of the failure diagnosis unit 800_ IV. The failure diagnosis unit 800_ IV shown in fig. 12 has a failure diagnosis unit 800_ I, a failure diagnosis unit 800_ V, and an OR block 861.
The failure diagnosis unit 800_ I performs diagnosis using a current value described with reference to fig. 5 to 8. However, in this example, in step S108 shown in fig. 5, the failure diagnosis unit 800_ I determines that the current flowing through the switching element SW _ A1H is normal. In this case, the fault diagnosis unit 800_ I outputs a signal (for example, "0") indicating that the current flowing in the switching element SW _ A1H is normal to the OR block 861, and returns to the processing of step S101. In step S107 shown in fig. 5, the failure diagnosis unit 800_ I determines that the current flowing through the switching element SW _ A1H is abnormal. The fault diagnosis unit 800_ I outputs a signal (for example, "1") indicating that the current flowing in the switching element SW _ A1H is abnormal to the OR block 861.
In this example, the output value "0" of the comparator 851 shown in fig. 6 is a signal indicating that the current flowing through the switching element SW _ A1H is normal. The output value "1" of the comparator 851 is a signal indicating that the current flowing through the switching element SW _ A1H is abnormal. The output of the comparator 851 is input to an OR block 861.
Thus, the failure diagnosis unit 800_ I shown in fig. 12 determines whether there is an abnormality in the current flowing through the switching element.
The failure diagnosis unit 800_ V performs diagnosis using a voltage value described with reference to fig. 9 and 10. However, in this example, in step S108 shown in fig. 9, failure diagnosis section 800_ V determines that the voltage applied to switching element SW _ A1H is normal. In this case, the fault diagnosis unit 800_ V outputs a signal (for example, "0") indicating that the voltage applied to the switching element SW _ A1H is normal to the OR block 861, and returns to the processing of step S111. In step S107 shown in fig. 9, the failure diagnosis unit 800_ V determines that the voltage applied to the switching element SW _ A1H is abnormal. The fault diagnosis unit 800_ V outputs a signal (for example, "1") indicating that the voltage applied to the switching element SW _ A1H is abnormal to the OR block 861.
In this example, the output value "0" of the comparator 851 shown in fig. 10 is a signal indicating that the voltage applied to the switching element SW _ A1H is normal. The output value "1" of the comparator 851 becomes a signal indicating that the voltage applied to the switching element SW _ A1H is abnormal. The output of the comparator 851 is input to an OR block 861.
Thus, failure diagnosis section 800_ V shown in fig. 12 determines whether or not there is an abnormality in the voltage applied to the switching element.
When both of the signals output from the failure diagnosis units 800_ I and 800_ V indicate normality, the OR block 861 determines that the switching element SW _ A1H is normal. When it is determined that the switching element SW _ A1H is normal, the OR block 861 outputs a signal (for example, "0") indicating that the switching element SW _ A1H is normal to the motor control unit 900.
When at least one of the signals output from the failure diagnosis units 800_ I and 800_ V indicates an abnormality, the OR block 861 determines that a failure has occurred in the switching element SW _ A1H. When determining that the switching element SW _ A1H is malfunctioning, the OR block 861 outputs a signal (for example, "1") indicating that the switching element SW _ A1H is malfunctioning to the motor control unit 900. Upon receiving a signal indicating that the switching element SW _ A1H has failed, the motor control unit 900 changes the control mode of the motor 200 from the normal control mode to the abnormal control mode.
In the example shown in fig. 12, the failure diagnosis unit 800_ IV performs failure diagnosis using both the detected current value and voltage value. Then, when at least one of the detected current value and voltage value is abnormal, it is determined that the switching element has failed. For example, when a fault occurs in the current sensor 150, although the current flowing through the switching element cannot be detected, even in this case, the presence or absence of the fault can be diagnosed using the detected voltage value. Further, for example, when a failure occurs in the voltage detection circuit 380, although the voltage applied to the switching element cannot be detected, even in this case, the presence or absence of the failure can be diagnosed by using the detected current value.
Fig. 13 shows another example of the functional blocks of the failure diagnosis unit 800_ IV. The failure diagnosis unit 800_ IV shown in fig. 13 has a failure diagnosis unit 800_ I, a failure diagnosis unit 800_ V, AND an AND block 862.
The operations of failure diagnosis unit 800_ I and failure diagnosis unit 800_ IV shown in fig. 13 are the same as the operations of failure diagnosis unit 800_ I and failure diagnosis unit 800_ IV shown in fig. 12. In the example shown in fig. 13, the respective outputs of the failure diagnosis unit 800_ I AND the failure diagnosis unit 800_ IV are input to the AND block 862.
If at least one of the signals output from failure diagnosis unit 800_ I AND failure diagnosis unit 800_ V indicates normality, AND block 862 determines that switching element SW _ A1H is normal. When it is determined that the switching element SW _ A1H is normal, the AND block 862 outputs a signal (for example, "0") indicating that the switching element SW _ A1H is normal to the motor control unit 900.
When both of the signals output from the failure diagnosis units 800_ I AND 800_ V indicate an abnormality, the AND block 862 determines that the switching element SW _ A1H has failed. When determining that the switching element SW _ A1H is malfunctioning, the AND block 862 outputs a signal (for example, "1") indicating that the switching element SW _ A1H is malfunctioning to the motor control unit 900. Upon receiving a signal indicating that the switching element SW _ A1H has failed, the motor control unit 900 changes the control mode of the motor 200 from the normal control mode to the abnormal control mode.
In the example shown in fig. 13, the failure diagnosis unit 800_ IV performs failure diagnosis using both the detected current value and voltage value. When both the detected current value and the detected voltage value are abnormal, it is determined that the switching element has failed. By determining a failure when both the current value and the voltage value are abnormal, the reliability of the determination of the failure can be improved.
In the above description, a method of diagnosing whether or not a failure occurs in a switching element is described by taking the power conversion apparatus 1000 as an example. The failure diagnosis method for diagnosing whether or not a switching element has a failure according to the embodiment of the present disclosure can be applied to various devices other than the power conversion device 1000. For example, these failure diagnosis methods can be applied to various converters such as a DC-DC converter, and various power generation systems such as a wind power generation system. The failure diagnosis method for diagnosing whether or not a switching element has a failure according to the embodiment of the present disclosure can be applied to an electric device having a switching element that repeatedly switches between on and off.
[ 2-4. Fault diagnosis of phase Using Current value ]
Next, a failure diagnosis method for diagnosing the presence or absence of a phase failure according to the present embodiment will be described. Here, a method of diagnosing whether a phase has a fault will be described by taking the power converter 1000 shown in fig. 1 as an example.
The switching elements of the 1 st and 2 nd inverters 120 and 130 are connected to the a-phase coil M1, the B-phase coil M2, and the C-phase coil M3 of the motor 200. When a failure occurs, if it can be determined which of the a-phase, the B-phase, and the C-phase the failure occurs, appropriate control can be performed according to the location of the failure. For example, if it can be determined that a failure has occurred in the a phase, two-phase energization control can be performed using the remaining B and C phases.
In this example, as shown in fig. 14, the controller 340 has a failure diagnosis unit 800P _ I as the failure diagnosis unit 800. The fault diagnosis unit 800P _ I diagnoses the presence or absence of a fault in a phase using the value of the current flowing through the switching element.
Fig. 15 shows an example of a functional block of the failure diagnosis unit 800P _ I. The failure diagnosis unit 800P _ I shown in fig. 15 has failure diagnosis units 800P _ IA, 800P _ IB, 800P _ IC. The failure diagnosis unit 800P _ IA performs failure diagnosis of the a phase using the value of the current flowing through the switching element belonging to the a phase. The fault diagnosis unit 800P _ IB performs fault diagnosis of the B phase using the value of the current flowing in the switching element belonging to the B phase. The fault diagnosis unit 800P _ IC performs fault diagnosis of the C phase using the value of the current flowing through the switching element belonging to the C phase.
Fig. 16 shows an example of a functional block of the failure diagnosis unit 800P _ IA. The failure diagnosis unit 800P _ IA shown in fig. 16 has failure diagnosis units 800_ I1H, 800_ I1L, 800_ I2H, 800_ I2L, and an OR block 870_ I.
In the example shown in fig. 2, switching elements SW _ A1H, SW _ A1L, SW _ A2H, and SW _ A2L are connected to the a-phase coil M1.
The current I _ A1H flowing through the switching element SW _ A1H and the gate control signal S _ A1H that turns on the switching element SW _ A1H are input to the fault diagnosis unit 800_ I1H. The current I _ A1L flowing through the switching element SW _ A1L and the gate control signal S _ A1L that turns on the switching element SW _ A1L are input to the fault diagnosis unit 800_ I1L. The current I _ A2H flowing in the switching element SW _ A2H and the gate control signal S _ A2H that turns on the switching element SW _ A2H are input to the fault diagnosis unit 800_ I2H. The current I _ A2L flowing in the switching element SW _ A2L and the gate control signal S _ A2L that turns on the switching element SW _ A2L are input to the fault diagnosis unit 800_ I2L.
The failure diagnosis unit 800_ I1H performs failure diagnosis using the current value described with reference to fig. 5 to 8. If it is determined in step S108 of fig. 5 that the switching element SW _ A1H is normal, the failure diagnosis unit 800_ I1H outputs a signal (for example, "0") indicating that the switching element SW _ A1H is normal to the OR block 870_ I, and returns to the processing of step S101. When it is determined in step S107 that the switching element SW _ A1H has failed, the failure diagnosis unit 800_ I1H outputs a signal (for example, "1") indicating that the switching element SW _ A1H has failed to the OR block 870_ I.
As with the failure diagnosis unit 800_ I1H, the failure diagnosis units 800_ I1L, 800_ I2H, 800_ I2L also perform failure diagnosis of the switching elements SW _ A1L, SW _ A2H, SW _ A2L. The outputs of the 4 fault diagnostic units 800_ I1H, 800_ I1L, 800_ I2H, 800_ I2L are each input to an OR block 870_ I.
In the case where the outputs of the 4 fault diagnosis units 800_ I1H, 800_ I1L, 800_ I2H, 800_ I2L all indicate normality, the OR block 870_ I determines that the a phase is normal. When it is determined that the a phase is normal, OR block 870_ I outputs a signal (for example, "0") indicating that the a phase is normal to motor control unit 900.
When any one of the output signals of the 4 fault diagnosis units 800_ I1H, 800_ I1L, 800_ I2H, 800_ I2L indicates a fault, the OR block 870_ I determines that the a-phase has failed. When it is determined that the a-phase has failed, OR block 870_ I outputs a signal (for example, "1") indicating that the a-phase has failed to motor control unit 900.
Similarly to the failure diagnosis unit 800P _ IA, the failure diagnosis units 800P _ IB and 800P _ IC shown in fig. 15 also diagnose whether or not there is a failure in the B-phase and the C-phase. The failure diagnosis units 800P _ IB, 800P _ IC output signals indicating the results of failure diagnosis to the motor control unit 900.
The motor control unit 900 can determine whether or not there is a failure in the a-phase, the B-phase, and the C-phase based on the output signals of the failure diagnosis units 800P _ IA, 800P _ IB, and 800P _ IC. When a failure occurs, the motor control unit 900 can determine which phase has failed based on the output signals of the failure diagnosis units 800P _ IA, 800P _ IB, and 800P _ IC. Since the failed phase can be specified, the motor control unit 900 can perform appropriate control according to the failure location. For example, the motor control unit 900 can perform two-phase energization control using the remaining two phases other than the failed phase.
[ 2-5. Fault diagnosis of phase Using Voltage value ]
Next, a fault diagnosis method for diagnosing whether a phase has a fault using a voltage value will be described. Here, a method of diagnosing whether a phase has a fault will be described by taking the power converter 1000 shown in fig. 1 as an example.
In this example, as shown in fig. 17, the controller 340 has a failure diagnosis unit 800P _ V as the failure diagnosis unit 800. The fault diagnosis unit 800P _ V diagnoses the presence or absence of a fault of a phase using the value of the voltage applied to the switching element.
Fig. 18 shows an example of a functional block of the failure diagnosis unit 800P _ V. The failure diagnosis unit 800P _ V shown in fig. 18 has failure diagnosis units 800P _ VA, 800P _ VB, 800P _ VC. The failure diagnosis unit 800P _ VA performs failure diagnosis of the a phase using the value of the voltage applied to the switching element belonging to the a phase. The failure diagnosis unit 800P _ VB performs failure diagnosis of the B phase using the value of the voltage applied to the switching element belonging to the B phase. The failure diagnosis unit 800P _ VC performs failure diagnosis of the C phase using the value of the voltage applied to the switching element belonging to the C phase.
Fig. 19 shows an example of a functional block of the failure diagnosis unit 800P _ VA. The failure diagnosis unit 800P _ VA shown in fig. 19 has failure diagnosis units 800_ V1H, 800_ V1L, 800_ V2H, 800_ V2L, and an OR block 870_ V.
The voltage V _ A1H applied to the switching element SW _ A1H and the gate control signal S _ A1H are input to the failure diagnosis unit 800_ V1H. The voltage V _ A1L applied to the switching element SW _ A1L and the gate control signal S _ A1L are input to the failure diagnosis unit 800_ V1L. The voltage V _ A2H applied to the switching element SW _ A2H and the gate control signal S _ A2H are input to the failure diagnosis unit 800_ V2H. The voltage V _ A2L applied to the switching element SW _ A2L and the gate control signal S _ A2L are input to the failure diagnosis unit 800_ V2L.
Failure diagnosis section 800_ V1H performs failure diagnosis using the voltage value described with reference to fig. 9 and 10. In step S108 of fig. 9, if it is determined that the switching element SW _ A1H is normal, the failure diagnosis unit 800_ V1H outputs a signal (for example, "0") indicating that the switching element SW _ A1H is normal to the OR block 870_ V, and returns to the processing of step S111. When determining in step S107 in fig. 9 that the switching element SW _ A1H has failed, the failure diagnosis unit 800_ V1H outputs a signal (for example, "1") indicating that the switching element SW _ A1H has failed to the OR block 870_ V.
As with the failure diagnosis unit 800_ V1H, the failure diagnosis units 800_ V1L, 800_ V2H, 800_ V2L also perform failure diagnosis of the switching elements SW _ A1L, SW _ A2H, SW _ A2L. The outputs of the 4 fault diagnostic units 800_ V1H, 800_ V1L, 800_ V2H, 800_ V2L are each input to an OR block 870_ V.
The OR block 870_ V determines that the a phase is normal when all of the output signals of the 4 fault diagnosis units 800_ V1H, 800_ V1L, 800_ V2H, 800_ V2L indicate normal. When it is determined that the a phase is normal, the OR block 870_ V outputs a signal (for example, "0") indicating that the a phase is normal to the motor control unit 900.
When any one of the output signals of the 4 fault diagnosis units 800_ V1H, 800_ V1L, 800_ V2H, 800_ V2L indicates a fault, the OR block 870_ V determines that the a phase has a fault. When it is determined that the a-phase has failed, OR block 870_ V outputs a signal (for example, "1") indicating that the a-phase has failed to motor control unit 900.
Similarly to the failure diagnosis unit 800P _ VA, the failure diagnosis units 800P _ VB and 800P _ VC shown in fig. 18 also diagnose whether or not there is a failure in the B-phase and the C-phase. The failure diagnosis units 800P _ VB, 800P _ VC output signals indicating the results of failure diagnosis to the motor control unit 900.
The motor control unit 900 can determine whether or not a failure occurs in the a-phase, the B-phase, and the C-phase based on the output signals of the failure diagnosis units 800P _ VA, 800P _ VB, and 800P _ VC. When a failure occurs, the motor control unit 900 can determine which phase has failed based on the output signals of the failure diagnosis units 800P _ VA, 800P _ VB, and 800P _ VC. Since the failed phase can be specified, the motor control unit 900 can perform appropriate control according to the failure location. For example, the motor control unit 900 can perform two-phase energization control using the remaining two phases other than the failed phase.
[ 2-6 ] Fault diagnosis of phase Using both Current and Voltage values ]
Next, a fault diagnosis method for diagnosing whether a phase has a fault or not using both a current value and a voltage value will be described. In this example, as shown in fig. 20, the controller 340 has a failure diagnosis unit 800P _ IV as the failure diagnosis unit 800. The fault diagnosis unit 800P _ IV diagnoses the presence or absence of a phase fault using both the value of the current flowing through the switching element and the value of the voltage applied to the switching element.
Fig. 21 shows an example of a functional block of the failure diagnosis unit 800P _ IV. The failure diagnosis unit 800P _ IV shown in fig. 21 has a failure diagnosis unit 800P _ IA, a failure diagnosis unit 800P _ VA, and an OR block 881A.
Failure diagnosis section 800P _ IA performs diagnosis using the current value described with reference to fig. 15 and 16. The failure diagnosis unit 800P _ VA performs diagnosis using a voltage value as described with reference to fig. 18 and 19.
When both the signals output from the failure diagnosis units 800P _ IA and 800P _ VA indicate normality, the OR block 881A determines that the a phase is normal. When it is determined that the a phase is normal, the OR block 881A outputs a signal (e.g., "0") indicating that the a phase is normal to the motor control unit 900.
When at least one of the signals output from failure diagnosis unit 800P _ IA and failure diagnosis unit 800P _ VA indicates an abnormality, OR block 881A determines that a phase has failed. When it is determined that the a phase has failed, the OR block 881A outputs a signal (for example, "1") indicating that the a phase has failed to the motor control unit 900.
The failure diagnosis unit 800P _ IV also has a failure diagnosis unit 800P _ IB, a failure diagnosis unit 800P _ VB, and an OR block 881B.
The failure diagnosis unit 800P _ IB performs diagnosis using the current value described with reference to fig. 15 and 16. The failure diagnosis unit 800P _ VB performs diagnosis using the voltage value described with reference to fig. 18 and 19.
When both of the signals output from the failure diagnosis units 800P _ IB and 800P _ VB indicate normality, the OR block 881B determines that the B phase is normal. When it is determined that the B phase is normal, the OR block 881B outputs a signal indicating that the B phase is normal to the motor control unit 900.
When at least one of the signals output from failure diagnosis unit 800P _ IB and failure diagnosis unit 800P _ VB indicates an abnormality, OR block 881B determines that a failure has occurred in phase B. When it is determined that the B phase has failed, the OR block 881B outputs a signal indicating that the B phase has failed to the motor control unit 900.
The failure diagnosis unit 800P _ IV also has a failure diagnosis unit 800P _ IC, a failure diagnosis unit 800P _ VC, and an OR block 881C.
The failure diagnosis unit 800P _ IC performs diagnosis using a current value as described with reference to fig. 15 and 16. The failure diagnosis unit 800P _ VC performs diagnosis using a voltage value as described with reference to fig. 18 and 19.
When both the signals output from the failure diagnosis unit 800P _ IC and the failure diagnosis unit 800P _ VC indicate normality, the OR block 881C determines that the C phase is normal. When it is determined that the C phase is normal, the OR block 881C outputs a signal indicating that the C phase is normal to the motor control unit 900.
OR block 881C determines that a failure has occurred in phase C when at least one of the signals output by failure diagnosis unit 800P _ IC and failure diagnosis unit 800P _ VC indicates an abnormality. When it is determined that the C phase has failed, the OR block 881C outputs a signal indicating that the C phase has failed to the motor control unit 900.
The motor control unit 900 can determine whether OR not there is a failure in the a-phase, the B-phase, and the C-phase based on the output signal of the OR block 881A, 881B, 881C. When a failure occurs, the motor control unit 900 can determine which phase has failed. Since the failed phase can be specified, the motor control unit 900 can perform appropriate control according to the failure location. For example, the motor control unit 900 can perform two-phase energization control using the remaining two phases other than the failed phase.
In the example shown in fig. 21, the failure diagnosis unit 800P _ IV performs failure diagnosis using both the detected current value and voltage value. For example, when a fault occurs in the current sensor 150, although the current flowing through the switching element cannot be detected, even in this case, the presence or absence of the fault can be diagnosed using the detected voltage value. Further, for example, when a failure occurs in the voltage detection circuit 380, although the voltage applied to the switching element cannot be detected, even in this case, the presence or absence of the failure can be diagnosed by using the detected current value.
Fig. 22 shows another example of the functional blocks of the failure diagnosis unit 800P _ IV. In contrast to the failure diagnosis unit 800_ IV shown in fig. 21, the failure diagnosis unit 800_ IV shown in fig. 22 has AND blocks 882A, 882B, AND 882C instead of OR blocks 881A, 881B, AND 881C.
In the example shown in fig. 22, the respective outputs of the failure diagnosing unit 800P _ IA AND the failure diagnosing unit 800P _ VA are input to the AND block 882A. The respective outputs of the fault diagnosing unit 800P _ IB AND the fault diagnosing unit 800P _ VB are input to the AND block 882B. The respective outputs of the fault diagnosis unit 800P _ IC AND the fault diagnosis unit 800P _ VC are input to the AND block 882C.
When at least one of the signals output from the failure diagnosing unit 800P _ IA AND the failure diagnosing unit 800P _ VA indicates normality, the AND block 882A determines that phase a is normal. In the case where it is determined that the a-phase is normal, the AND block 882A outputs a signal (e.g., "0") indicating that the a-phase is normal to the motor control unit 900.
When both of the signals output by the failure diagnosis unit 800P _ IA AND the failure diagnosis unit 800P _ VA indicate an abnormality, the AND block 882A determines that a failure has occurred in phase a. When it is determined that the a-phase has failed, the AND block 882A outputs a signal (e.g., "1") indicating that the a-phase has failed to the motor control unit 900.
When at least one of the signals output from the failure diagnosis units 800P _ IB AND 800P _ VB indicates normality, the AND block 882B determines that phase B is normal. In the case where it is determined that the B-phase is normal, the AND block 882B outputs a signal indicating that the B-phase is normal to the motor control unit 900.
When both of the signals output from the failure diagnosis units 800P _ IB AND 800P _ VB indicate an abnormality, the AND block 882B determines that a failure has occurred in phase B. When it is determined that the B phase has failed, the AND block 882B outputs a signal indicating that the B phase has failed to the motor control unit 900.
If at least one of the signals output from failure diagnosis unit 800P _ IC AND failure diagnosis unit 800P _ VC indicates normality, AND block 882C determines that phase C is normal. In the case where it is determined that the C-phase is normal, the AND block 882C outputs a signal indicating that the C-phase is normal to the motor control unit 900.
When both of the signals output by the failure diagnosis unit 800P _ IC AND the failure diagnosis unit 800P _ VC indicate an abnormality, the AND block 882C determines that a failure has occurred in phase C. When it is determined that the C-phase has failed, the AND block 882C outputs a signal indicating that the C-phase has failed to the motor control unit 900.
The motor control unit 900 can determine whether OR not there is a failure in the a-phase, the B-phase, and the C-phase based on the output signals of the OR blocks 882A, 882B, and 882C. When a failure occurs, the motor control unit 900 can determine which phase has failed. Since the failed phase can be specified, the motor control unit 900 can perform appropriate control according to the failure location.
In the example shown in fig. 22, the failure diagnosis unit 800P _ IV performs failure diagnosis using both the detected current value and voltage value. By determining that a failure has occurred when both the current value and the voltage value are abnormal, the reliability of the determination of a failure can be improved.
The failure diagnosis method according to the embodiment of the present disclosure is not limited to the power conversion device 1000 including the inverter unit 100 having 3H bridges as shown in fig. 2, and can be suitably used for a power conversion device that drives a motor in which one ends of coils are Y-connected to each other.
Fig. 23 schematically shows a circuit configuration of an inverter unit 100A having a single inverter 140 according to a modification of the present embodiment.
In this example, the inverter unit 100A is connected to a motor 200 having three-phase coils with one ends connected to each other in a Y-shape. The failure diagnosis method according to the embodiment can be applied to, for example, a motor using three-phase current, and can also be applied to a motor having coils in which one ends are connected to each other in a delta connection. The a-phase branch of the inverter 140 has a low-side switching element SW _ AL, a high-side switching element SW _ AH, and a shunt resistor S _ a. The phase-B branch has a low-side switching element SW _ BL, a high-side switching element SW _ BH, and a shunt resistor S _ B. The phase C branch has a low-side switching element SW _ CL, a high-side switching element SW _ CH, and a shunt resistor S _ C.
The controller 340 can diagnose the presence or absence of a failure in the plurality of switching elements included in the inverter 140 by the same method as the failure diagnosis method described above. The controller 340 can diagnose the presence or absence of a failure in the a-phase, the B-phase, and the C-phase by the same method as the failure diagnosis method described above.
When the inverter 140 is not malfunctioning, the controller 340 controls the motor 200 by, for example, three-phase energization control. When inverter 140 has failed, controller 340 performs control for stopping driving motor 200, for example.
In this way, the controller 340 can change the control of the motor 200 according to whether the inverter 140 is normal or abnormal.
(embodiment mode 2)
Fig. 24 schematically shows a typical configuration of an electric power steering apparatus 3000 according to the present embodiment.
Vehicles such as automobiles generally have an electric power steering apparatus. The electric power steering apparatus 3000 of the present embodiment includes a steering system 520 and an assist torque mechanism 540 that generates an assist torque. The electric power steering apparatus 3000 generates an assist torque that assists a steering torque of a steering system generated by a driver operating a steering wheel. The operation load of the driver can be reduced by the assist torque.
The steering system 520 can be configured by, for example, a steering wheel 521, a steering shaft 522, universal joints 523A and 523B, a rotating shaft 524, a rack-and-pinion mechanism 525, a rack shaft 526, left and right ball joints 552A and 552B, tie rods 527A and 527B, knuckles 528A and 528B, and left and right steered wheels 529A and 529B.
The assist torque mechanism 540 is constituted by, for example, a steering torque sensor 541, an Electronic Control Unit (ECU)542 for an automobile, a motor 543, a speed reduction mechanism 544, and the like. The steering torque sensor 541 detects a steering torque in the steering system 520. ECU542 generates a drive signal based on the detection signal of steering torque sensor 541. The motor 543 generates an assist torque corresponding to the steering torque based on the drive signal. The motor 543 transmits the generated assist torque to the steering system 520 via the speed reduction mechanism 544.
The ECU542 includes, for example, the controller 340 and the drive circuit 350 of embodiment 1. An electronic control system with ECU as core is built in the automobile. In the electric power steering apparatus 3000, for example, a motor drive unit is configured by the ECU542, the motor 543, and the inverter 545. The motor module 2000 of embodiment 1 can be suitably used in this system.
Embodiments of the present disclosure are also suitably used for shift-by-wire technologies such as shift-by-wire, steer-by-wire, and brake-by-wire, and motor control systems for traction motors and the like. For example, the EPS in which the motor control method of the embodiment of the present disclosure is installed can be mounted on an autonomous vehicle corresponding to levels 0 to 4 (automated reference) stipulated by the japan government and the u.s.department of transportation and provincial road traffic safety administration (NHTSA).
Industrial applicability
Embodiments of the present disclosure can be widely applied to various apparatuses having various motors, such as a dust collector, a blower, a ceiling fan, a washing machine, a refrigerator, and an electric power steering apparatus.
Description of the reference symbols
100. 100A: an inverter unit; 101: a power source; 120: 1 st inverter; 130: a2 nd inverter; 140: an inverter; 150: a current sensor; 200: a motor; 300: a control circuit; 310: a power supply circuit; 320: an angle sensor; 330: an input circuit; 340: a microcontroller; 350: a drive circuit; 360: a ROM; 1000: a power conversion device; 2000: a motor module; 3000: provided is an electric power steering device.

Claims (11)

1. A fault diagnosis method for diagnosing whether or not a fault occurs in a switching element that is repeatedly switched between ON and OFF and is included in an electrical device, the fault diagnosis method comprising:
determining whether or not a current flowing in the switching element when the switching element is controlled to the on state is smaller than a prescribed current;
detecting a time during which the current flowing in the switching element is smaller than the predetermined current when the current flowing in the switching element is smaller than the predetermined current;
determining whether the detected time is equal to or longer than a predetermined time;
counting the number of times that the detected time is equal to or longer than the predetermined time, when the detected time is equal to or longer than the predetermined time;
determining whether or not the counted total number of times is equal to or greater than a predetermined number of times;
outputting a first signal for determining that the switching element is abnormal when the counted total number of times is equal to or greater than the predetermined number of times;
determining whether or not a source-drain voltage of the switching element when the switching element is controlled to be in an on state is equal to or higher than a predetermined voltage;
detecting a time during which the source-drain voltage is equal to or higher than a predetermined voltage when the source-drain voltage is equal to or higher than the predetermined voltage;
determining whether the detected time is equal to or longer than a predetermined time;
outputting a second signal that determines that the switching element is abnormal when the detected time is equal to or longer than the predetermined time; and
when either one of the first signal and the second signal or both of the first signal and the second signal are output, it is determined that the switching element has failed.
2. The failure diagnostic method according to claim 1,
the fault diagnosis method further comprises the following steps: when the current flowing through the switching element is not less than the predetermined current, it is determined that the switching element is normal.
3. The failure diagnosis method according to claim 1,
the fault diagnosis method further comprises the following steps: when the detected time is not equal to or longer than a predetermined time, it is determined that the switching element is normal.
4. The failure diagnosis method according to claim 1,
the fault diagnosis method further comprises the following steps: when the counted total number of times is not equal to or greater than the predetermined number of times, it is determined that the switching element is normal.
5. The failure diagnosis method according to claim 1,
the switching element is a transistor which is,
the current flowing in the switching element is a current flowing between the source and the drain of the transistor.
6. The failure diagnosis method according to claim 1,
the electric apparatus is a power conversion device that converts electric power from a power supply into electric power supplied to a motor,
the switching element is a switching element provided in the power conversion device.
7. A motor control method that executes the failure diagnosis method according to claim 6,
controlling the motor in a1 st control mode when it is determined that the switching element is not malfunctioning,
when it is determined that the switching element has failed, the motor is controlled in a2 nd control mode different from the 1 st control mode.
8. An electrical apparatus, comprising:
a switching element; and
a control circuit for controlling switching operation of on/off of the switching element,
the control circuit performs the following processing:
determining whether or not a current flowing in the switching element when the switching element is controlled to the on state is smaller than a prescribed current,
detecting a time when the current flowing in the switching element is smaller than the predetermined current,
determining whether the detected time is equal to or longer than a predetermined time,
counting the number of times that the detected time is equal to or longer than the predetermined time when the detected time is equal to or longer than the predetermined time,
determining whether or not the counted total number of times is equal to or more than a predetermined number of times,
outputting a first signal for determining that the switching element is abnormal when the counted total number of times is equal to or greater than the predetermined number of times,
determining whether or not a source-drain voltage of the switching element when the switching element is controlled to be in an on state is equal to or higher than a predetermined voltage,
detecting a time when the source-drain voltage is equal to or higher than a predetermined voltage when the source-drain voltage is equal to or higher than the predetermined voltage,
determining whether the detected time is equal to or longer than a predetermined time,
outputting a second signal for determining that the switching element is abnormal when the detected time is equal to or longer than the predetermined time,
when either one of the first signal and the second signal or both of the first signal and the second signal are output, it is determined that the switching element has failed.
9. The electrical device of claim 8,
the electric device is a power conversion device that converts electric power from a power source into electric power to be supplied to a motor,
the switching element is a switching element provided in the power conversion device.
10. A motor module having:
a motor; and
the electrical device of claim 9.
11. An electric power steering apparatus having the motor module of claim 10.
CN201880052833.9A 2017-09-25 2018-06-18 Fault diagnosis method, motor control method, power conversion device, motor module, and electric power steering device Active CN111033287B (en)

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